1. Field of the Invention
The present invention relates to swimming pool cover extension and retraction systems and, more particularly, to a clutch for selectively actuating cords to extend the cover or a roller to retract the cover and having a compensator for accommodating for changes in relative length of the cords over time or as a function of the squareness of the pool.
2. Description of Related Prior Art
Particularly residential swimming pools are not in constant use with adult supervision. During such periods of non use, a swimming pool is in the nature of an attractive nuisance to the extent that children may play with the water or float toys on the water whether such children are by the side of the pool or actually in the pool. Without adult supervision, such children may come to harm by falling into the pool or by panicking when in the pool. To reduce the likelihood of harm to such children, many jurisdictions require a childproof fence be erected about the pool and having a latching gate not operable by a child. Such fences are generally unsightly and often not sufficiently effective to keep children away from the pool.
To alleviate the burden of having to erect a fence about a residential pool, various manufacturers provide covers for swimming pools that may be installed or removed with more or less difficulty. Many of these covers are of plastic impregnated canvas that must be unfolded and dragged across the pool with subsequent attachment to the sides of the pool. Generally, two or more persons are needed to effect this task. To uncover the pool, this process is reversed. Thereafter, a storage place must be available for the rather bulky folded cover. Because of the work involved in securing, removing and storing pool covers of this type, they have found little popularity.
Automated pool cover extension and retraction systems have been available for a period of years. Such systems generally include a roller rotatably mounted at one end of a pool from which a cover is extended across a pool by motor driven pulleys retracting cords attached to the end of the cover. Retraction is achieved by rotating the roller to wind the cover thereof. Previously used mechanisms for accomplishing these results generally tend to be bulky, incorporate a plurality of parts and fixtures and require significant maintenance efforts to operate satisfactorily. Furthermore, the extension apparatus generally includes two cords attached to opposed sides of the free end of the cover. The length of these two cords is different and over time one cord will stretch more than the other. Unless such change in relative length is addressed by the apparatus, the cover will become skewed and effective operation will be compromised. Moreover, the winding of the cords upon a common pulley or upon separate pulleys will not be uniform and one cord may become wrapped about its pulley more quickly than the other cord, also resulting in skewing of the cover. As both the pulley(s) and the roller must be motor driven, two separate motors have been used to avoid the mechanical complexity of having a single motor selectively driving both the pulley(s) and the roller.
Aside from the safety issues attendant extending a pool cover across a pool during non use, several practical benefits are also achieved. First, such a cover prevents leaves and other debris from falling into the pool. Whatever debris may come to rest upon the cover is relatively easily removed as most pool covers can be walked upon by a person.
In climates where a pool is heated, a pool cover serves a very beneficial purpose of retaining the heat. That is, the cover prevents heat transfer from the water of the pool by radiation and by convection. Furthermore, evaporation as a result of wind blowing there across, another element of heat loss, is essentially avoided. Thereby, the costs of heating a pool are significantly reduced by such reduction of heat loss.
Finally, for safety reasons, a pool cover should be sufficiently robust to permit an adult to walk there across without fear of the pool cover ripping and resulting in the person falling there through. Obviously, such strength embodied in the pool cover will prevent any child venturing onto the pool cover from falling into the water and drowning.